1. Field of the Invention
The present invention relates to digital multimedia stream distribution, and more particularly to a system and method to protect digital multimedia streams from unauthorized editing. The present invention may be employed for a plurality of different applications and may be particularly useful with regard to the commercial distribution of copyrighted works or other proprietary subject matter over either a public network or a physical storage medium, for example, DVD.
2. Description of the Related Art
With the advent of public computer networks, and the Internet, authors of digital media have an inexpensive means to distribute their works to a growing and massive audience. Consumers thus benefit from improved access to information and greater convenience. While artists and businesses benefit from distribution channels with enormous potential to reach a wide and varying client base.
Despite this potential, content providers have been reluctant to embrace this market. One hurdle to be overcome is a fundamental problem in the digital world, as opposed to the analog world. This fundamental problem is that an unlimited number of perfect editing operations can be made on any piece of digital content. A perfect edition means that no degradation is introduced by the editing operation. For example, one can easily get rid of some or all the commercials intentionally embedded in a movie. The resulting “commercial-free” movie can be distributed without quality difference from the unedited one.
The research area of “copyright protection” brings adequate solutions to this problem. Two typical technologies for copyright protection include “cryptography” and “steganography.”
“Cryptography” is a field covering numerous techniques for scrambling information conveying messages so that when the message is conveyed between the sender and the receiver, a malicious party who intercepts this message cannot read it, edit it nor extract useful information from it. Once the content has been scrambled it cannot be used until it is unscrambled. Unscrambling requires the possession of a special key.
“Steganography” is a field covering numerous methods for hiding an informational message within some other medium in such a way that a malicious party who intercepts the medium carrying the hidden message does not know it contains this hidden message, for example a hidden watermark. Assuming the malicious party knows that the medium contains a hidden message, steganography makes it extremely difficult to extract it for further reading or editing.
Although these technologies provide protection from copying documents, a need exists to prevent the editing of documents by the addition or removal of portions of the document.